Structural arrangement for the open-circuit liquid cooling of gas turbine vanes are shown in U.S. Pat. No. 3,446,481--Kydd. The cooling of the vanes is accomplished by means of a large number of spanwise-extending subsurface cooling channels. Arrangements for metering liquid coolant to such cooling channels are shown in U.S. Pat. No. 3,658,439--Kydd, in U.S. Pat. No. 3,804,551--Moore, and in U.S. Pat. No. 3,856,433--Grondahl et al.
The use of serpentine cooling channel construction for open-circuit liquid cooling of turbine vanes and platforms is disclosed in U.S. Pat. No. 3,844,679--Grondahl et al. and U.S. Pat. No. 3,849,025--Grondahl. In each of the latter two patents each convoluted cooling channel is fed liquid coolant directly from a gutter integral with the rotor via a coolant supply conduit.
Constructions by which the coolant discharge from liquid-cooled gas turbine buckets is collected to enable recirculation thereof are disclosed in U.S. Pat. No. 3,736,071--Kydd and in the U.S. Pat. No. 3,816,022--Day.
All of the aforementioned patents are incorporated by reference.
A coolant recovery system for a shrouded opencircuit, liquid-cooled gas turbine is set forth as the embodiment in FIGS. 1, 2 and 3 of the Day patent wherein the coolant discharge (gas or vapor and excess liquid coolant) from the turbine bucket vanes passes via convergent-divergent nozzles into the annular cavity defined by the shroud, the casing and the labyrinth seals. The Day invention, however, does not address itself to the problem of leakage into or out of this cavity.
The leakage of high energy gas from the working fluid stream into this cavity introduces a significant penalty in stage performance, thereby depressing the thermal efficiency of the cycle. Particularly with liquidcooled turbines leakage into the cavity should be minimized to avoid the generation of corrosive agents by the interaction between the by-products of combustion in the working fluid and the liquid coolant (e.g. water). Similarly, leakage from the aforementioned cavity into the working fluid stream should be avoided in order that the liquid coolant (usually water) consumption can be kept within acceptable limits.
Thus, regardless of the relative pressure conditions in the cavity and the working fluid stream an effective, low-cost seal is required between adjacent shroud plates. The instant invention is directed to the solution of this problem.